NetBSD/etc/autofs/include_nis_nullfs

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#!/usr/bin/awk -f
#-
# Copyright (c) 2017 G. Paul Ziemba
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $NetBSD: include_nis_nullfs,v 1.1 2018/01/09 03:31:14 christos Exp $
#
#
# /etc/autofs/include_nis_nullfs
#
# automountd Directory Services script for NIS
#
# SYNOPSIS
# include_nis_nullfs <mapname>
#
# include_nis_nullfs <mapname> <key>
#
# DESCRIPTION
#
# This script provides a Directory Services map for automountd
# based on NIS. Please see auto_master(5) for general information.
#
# The first form, with one argument, emits the entire named NIS map.
# The second form, with two arguments, emits the map entry for the
# key given in the second argument.
#
# This script attempts to determine the names and IP addresses
# of the local host. Map entries matching the local host are
# rewritten to specify nullfs mounts (instead of the default
# NFS) to reduce access overhead in the kernel.
#
# If a map entry contains multiple location fields, it is not changed.
#
# Populate list of names and IP addrs thet mean "this host"
# into myhostnames array
BEGIN {
#
# Set self hostnames
#
"hostname -s" | getline;
myhostnames[$0] = 1;
"hostname -f" | getline;
myhostnames[$0] = 1;
myhostnames["localhost"] = 1
"hostname -f" | getline;
localdomain=$0
myhostnames["localhost."localdomain] = 1
while ("ifconfig" | getline) {
if ($1 == "inet") {
myhostnames[$2] = 1;
}
}
# debug
# print "--- hostname list start ----"
# for (i in myhostnames) {
# print i
# }
# print "--- hostname list end ----"
if (ARGC == 2) {
# mapname only
while ("ypcat -k " ARGV[1] | getline) {
proc_mapline(1)
}
}
if (ARGC == 3) {
# mapname and keyname
while ("ypmatch " ARGV[2] " " ARGV[1] | getline) {
proc_mapline(0)
}
}
exit 0
}
function is_self(hostname)
{
if (myhostnames[hostname]) {
return 1
}
return 0
}
#
# Lines are of the form [key] [-opts] location1 [... locationN]
#
# indicate index of key field with first positional parameter
# 1 means keyfield is the first field
# 0 means keyfield is not present
#
function proc_mapline(keyfield)
{
optionsfield = 0
locationfield = 0
locationcount = 0
for (i=keyfield+1; i <= NF; ++i) {
if (!optionsfield) {
if ($i ~ /^-/) {
# the first options field found on the line
optionsfield = i;
continue
}
}
# Assumption: location contains colon (":")
if (optionsfield && ($i ~ /:/) && ($i !~ /^-/)) {
++locationcount
if (!locationfield) {
# the first location field found on the line
locationfield = i
}
}
}
#
# If location not found, do not modify.
#
# If there is more than one location, do not modify. Rationale:
# Options are applied to all locations. We ca not have "nullfs"
# for only some locations and "nfs" for others for a given
# map key (i.e., a line). The usual reason for multiple
# locations is for redundancy using replicated volumes on
# multiple hosts, so multiple hosts imply fstype=nfs (the
# FreeBSD default for automounter maps).
#
# Hypothetically there could be a map entry with multiple
# locations all with host parts matching "me". In that case,
# it would be safe to rewrite the locations and specify
# nullfs, but the code does not handle this case.
#
if (locationcount == 1) {
#
# We have a line with exactly one location field
#
# Assumption: location has no more than one colon (":")
#
n=split($locationfield,location,":")
if (is_self(location[1])) {
$locationfield = ":" location[2]
if (optionsfield) {
# append to existing options
$optionsfield = $optionsfield ",fstype=nullfs"
} else {
# sneak in ahead of location
$locationfield = "-fstype=nullfs " $locationfield
}
}
}
print
}